High-precision interferometric testing of spherical mirrors with long radius of curvature

Klaus R. Freischlad; Michael F. Kuechel; Wolfgang Wiedmann; Winfried M. Kaiser; Maximilian Mayer

doi:10.1117/12.51046

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1 January 1991 High-precision interferometric testing of spherical mirrors with long radius of curvature

Klaus R. Freischlad, Michael F. Kuechel, Wolfgang Wiedmann, Winfried M. Kaiser, Maximilian Mayer

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Proceedings Volume 1332, Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection; (1991) https://doi.org/10.1117/12.51046
Event: 34th Annual International Technical Symposium on Optical and Optoelectronic Applied Science and Engineering, 1990, San Diego, CA, United States

Abstract

Surface deviations of spherical mirrors from a best fitting, mathematically ideal sphere were measured to an absolute precision of 0.25 nm rms. Because of the long radius of curvature, a Hindle-type arrangement was used as interferometric setup, resulting in a test arm length of about 1.4 m. A special calibration procedure was implemented to eliminate systematic, setup-dependent errors. A very fast data acquisition technique was combined with real-time wavefront averaging to eliminate the effects of random errors, such as wavefront variations due to the turbulent atmosphere in the beam path. For the evaluation of one mirror surface, all in all 400,000 individual wavefront measurements at 400 x 400 points were combined, requiring an overall measurement time of only one to two days.

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Klaus R. Freischlad, Michael F. Kuechel, Wolfgang Wiedmann, Winfried M. Kaiser, and Maximilian Mayer "High-precision interferometric testing of spherical mirrors with long radius of curvature", Proc. SPIE 1332, Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection, (1 January 1991); https://doi.org/10.1117/12.51046

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